As much as I hate it and would love to think that pagination is just a publication pipedream, it's not.
Some online publications have spent (and will spend if they're interested in making $) significant time and $ A/B testing various levels of pagination such that their sites are optimized so that there are just fewer pages than their readership is unwilling to tolerate.
The end result is that their sites are optimized to make the most amount of money. If it didn't improve their revenues, they wouldn't be doing it.
Of course, there are copycats that don't do the testing, don't optimize for their niche of readers, and are probably losing both money and readers because of it.
We can argue about publications adopting different business models, but that's a different story. Advertisers pay a premium for engaged, targeted niche audiences that match their products/services. That's the reality of the online advertising market.